<template>
  <div>
    <p>请选择你要购买的书籍</p>
    <ul v-for="(obj,index) in arr" :key="index">
      <li >{{obj.name}}
        <button @click="addFn(index)">买书</button>
      </li>
    </ul>
    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="(obj,index) in arr" :key="index">
        <th>{{index+1}}</th>
        <th>{{obj.name}}</th>
        <th>{{obj.price}}</th>
        <th>{{obj.count}}</th>
        <th>{{obj.count*obj.price}}</th>
      </tr>
    </table>
    <p>总价格为: {{allPrice}}</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      num:0,
      price:0,
 
      arr: [
        {
          name: "水浒传",
          price: 107,
          count: 0,
        },
        {
          name: "西游记",
          price: 192,
          count: 0,
        },
        {
          name: "三国演义",
          price: 219,
          count: 0,
        },
        {
          name: "红楼梦",
          price: 178,
          count: 0,
        },
      ],
    };
  },
  methods: {
    addFn(id){
    this.arr[id].count++
    }
  },
  computed: {
    allPrice(){
   return   this.arr.reduce((prev,item)=>prev+=(item.price)*(item.count),0)
    }
  }
};
</script>